Hollow product, fluid processing system and joining method of hollow members

ABSTRACT

A connecting portion ( 10   c ) of a container ( 10 ) of a catalyst converter is formed with a joining portion ( 15 ) to be joined to a joining portion ( 16 ) of a flange member ( 11 ) by spinning working, and the joining portion ( 15 ) formed by the spinning working is joined to the joining portion ( 16 ) of the flange member ( 11 ) by friction welding. One of the connecting portion ( 10   c ) of the container of the catalyst converter and the flange member ( 11 ) is extended so as to be disposed radially inward of the joining portions ( 15 ) and ( 16 )

FIELD OF THE INVENTION

[0001] The invention relates to a hollow product, a fluid processingsystem and a joining method of hollow members, and more particularly, toa hollow product comprising joined hollow members for allowing fluid toflow therein, a fluid processing system comprising joined hollowmembers, at least one of the hollow members having a processing functionportion which carried out a predetermined processing with respect tofluid flowing therein. The invention also relates to a joining methodfor joining hollow members to each other.

BACKGROUND OF THE INVENTION

[0002] As a hollow product for allowing fluid to flow therein, anexhaust system for flowing and discharging exhaust gas, or the fluid, isconnected to a combustion engine such as an internal combustion enginefor a vehicle. As shown in FIG. 19, the exhaust system comprises hollowmembers such as an exhaust manifold 1, a catalyst converter 2, a pipe 3,a pre-muffler 4 and a main muffler 5. The catalyst converter 2 purifiesthe exhaust gas discharged from a combustion engine and which flows fromthe exhaust manifold by causing chemical reactions such as oxidation andreduction of the exhaust gas to take place. The pre-muffler 4 and themain muffler 5 bring high-pressure exhaust gas flowing from the catalystconverter 2 and the pipe 3 close to atmospheric pressure for reducingnoise.

[0003] The hollow members such as the exhaust manifold 1, the catalystconverter 2, the pipe 3, the pre-muffler 4 and the main muffler 5 aredetachably connected to an adjacent hollow members so that the hollowmember can easily be replaced by another member when it is damaged.Therefore, the hollow members are provided at ends of containers orconnection pipes with flange members capable of being fastened by meansof bolts, and thus the hollow members are formed into one unit.

[0004]FIG. 20 shows related art for joining a flange member 11′ as onehollow member to the other hollow member 10′ such as a connection pipe.In this related art, a plate is formed with a hole to form the hollowflange member 11′, the hollow member 10′ such as the connection pipe isinserted through the flange member 11′, and the two members are joinedto each other by cladding welding.

[0005] For example, Japanese Patent Applications Laid-open No. 9-234877,No. 10-29077, No. 9-242540 and No. 63-132790 disclose a technique forjoining ends of pipe-like hollow members in their longitudinal directionby friction welding.

[0006] This Japanese Patent Application Laid-open No. 63-132790discloses a manufacturing method for a rotation shaft wherein an endsurface of a pipe-like rotation shaft constituent member is frictionwelded to an end surface of another pipe-like rotation shaft constituentmember so as to form a rotation shaft body. In this method, the rotationshaft constituent members are friction welded to each other in a statewhere a core member for preventing generation of burrs is inserted intothe pipes of the rotation shaft constituent members, and. Thispublication describes that this core member is formed such that itsouter diameter is substantially the same as an inner diameter of therotation shaft constituent member. The publication also describes thatthe core member is inserted into the pipe of the rotation shaftconstituent member which is held in its stationary state before thefriction welding operation.

[0007] Japanese Patent Publication No. 2957163 discloses an exhaustsystem part of a double heat insulation structure comprising an innerpipe whose opposite ends are reduced in diameter in a tapered state andan outer pipe whose opposite ends are reduced in diameter in a taperedstate, wherein the inner and outer pipes are disposed with a gapinterposed therebetween. This publication also discloses a manufacturingmethod of the exhaust system part. In this publication, there aredescribed that “tip ends of both tapered diameter-reduced portions ofthe outer pipe are extended by a spinning roller to push the tip endsagainst an outer peripheral surface of a connecting portion of the innerpipe for plastically deforming the tip ends, and the extended connectingportion and a connecting portion of the inner pipe are connected to eachother, thereby integrally forming the inner and outer pipes,” or that “ashock absorbing member is interposed between steps formed on connectingportions of the inner and outer pipes by drawing, thereby preventing theinner and outer pipes from coming into contact with each other byoscillation, the inner and outer pipes are allowed to slide relativelyin their axial direction so that a stress caused by difference intemperature, and therefore in coefficient of thermal expansion, betweenthe inner and outer pipes is moderated to enhance the durability”(paragraph numbers are 0024, 0029 and 0030).

[0008] Among the above conventional techniques, the one shown in FIG. 20for cladding welding the plate materials constituting the flange membersand the pipe inserted into the holes of the flange members has a problemthat a weight of the hollow product is increased due to the cladding bywelding. This problem is serious especially in the case of an exhaustsystem of a moving body having an internal combustion engine such as anautomobile. Further, in this related art, it is necessary to takeprotective measures such as a cover for protecting the hollow member anda welding apparatus from spatter generated at the time of cladding bywelding, and there is a problem that equipment cost is increased.Furthermore, in this related art, when the hollow product is used forallowing fluid to flow therein, in order to reliably secure theair-tightness against fluid flowing in the hollow product, it isnecessary to continuously carry out the cladding by welding over theentire periphery, and there is a problem that joining quality by highlyprofessional welding is required. Further, there is a problem that thequality of the joined hollow members is varied due to thermal effect bythe welding.

[0009] Further, among the above conventional techniques, the one forjoining the pipes by friction welding has a problem that the joiningquality is unstable when end surfaces of relatively thin hollow membersare joined. As shown in FIG. 21, in Japanese Patent ApplicationsLaid-open No. 9-234877, No. 10-29077 and No. 9-242540, a burr isgenerated not only on outer sides of hollow members 30′ and 31′, butalso on inner sides thereof due to the friction welding. When the hollowproduct is used for allowing the fluid therein to carry out apredetermined processing, since the burr generated on the inner sideprojecting therefrom becomes a flow resistance of the fluiddeteriorating the flow efficiency, it is necessary to remove the burr.However, as described in Japanese Patent Application Laid-open No.63-132790 also, it is difficult to remove the burr generated on theinner side. Therefore, in the related art for joining the pipes byfriction welding, it was not possible to enhance the flow efficiency offluid flowing in the hollow member. The core member in Japanese PatentApplication Laid-open No. 63-132790 is merely inserted into the pipe ofthe rotation shaft constituent member, and there is no descriptionconcerning whether the core member is pulled out from the rotation shaftconstituent member after the friction welding of the rotation shaftconstituent members, or the core member is left therein.

[0010] Among the above conventional techniques, in Japanese PatentPublication No. 2957163, the connecting portion of the outer pipe isconnected to the connecting portion of the inner pipe directly orthrough a shock absorbing member merely by drawing using the spinningroller. Therefore, there is a problem that the connection between theinner and outer pipes is weak.

DISCLOSURE OF THE INVENTION

[0011] The invention has been accomplished in view of the aboveproblems, and it is an object of the invention to provide a light-weighthollow product in which hollow members are easily and reliably joined toeach other without generating a burr on an inner side of the hollowproduct and fluid can flow in the hollow product efficiently. It isanother object of the invention to provide a fluid processing system forsubjecting the fluid flowing in the hollow product to a predeterminedprocessing, and to provide a joining method of the hollow members.

[0012] According to a first aspect of the invention, there is provided ahollow product comprising hollow members joined to each other forallowing fluid to flow therein, wherein one of the hollow member isformed with a joining portion to be joined to the other hollow member byspinning working.

[0013] According to this aspect, since the one hollow member is formedwith the joining portion by the spinning working, it is possible toprovide a light-weight hollow product having excellent flow efficiencyin which the joining portion is stably and reliably formed over theentire periphery of the one hollow member.

[0014] In the above aspect, the joining portion of the one hollow memberformed by the spinning working can be joined to the other hollow memberby friction welding.

[0015] With this arrangement, since the joining portion formed on theone hollow member is joined to the other hollow member by frictionwelding, it is possible to provide a hollow product for allowing thefluid to flow therein in which the hollow member is easily and reliablyjoined over the entire periphery without being affected by the thicknessof the hollow member and a weight of the hollow product is reduced.

[0016] In the above aspect, any of the hollow members can be extended soas to be disposed in the joining portion.

[0017] With this arrangement, since any of the hollow members can beextended so as to be disposed radially inward of the joining portion,burr is prevented from being generated inside the hollow product due tothe friction welding. Also, because the inside is formed continuously,it is possible to provide a hollow product having higher flow efficiencyof the fluid.

[0018] Here, the joining portion can be formed such as to projectoutward in the intermediate portion of the one hollow member, the onehollow member can be inserted into the other hollow member, and thejoining portion of the one hollow member can be joined to the otherhollow member by the friction welding. A portion of the one hollowmember from the connecting portion toward the tip end is locatedradially inward of the friction welding portion. Therefore, a burr isprevented from being generated inside the hollow product due to thefriction welding.

[0019] Further, the joining portion is formed at an intermediate portionof the one hollow member stepwisely such as to be reduced in diametertoward the tip end, the one hollow member is inserted into the otherhollow member, and the joining portion stepwisely formed on the onehollow member is joined to the tip end of the other hollow member byfriction welding. With this structure, since the one hollow member islocated radially inward of the friction welding portion, a burr isprevented from being generated inside the hollow product due to thefriction welding.

[0020] Further, the joining portion may be formed such that the tip endthereof is increased in diameter wider than the intermediate portion ofthe one hollow member, the other hollow member is inserted into the onehollow member, and the diameter-increased tip end of the one hollowmember and a portion of the other hollow member corresponding to the tipend are joined by the friction welding. Since the portion of the otherhollow member from the connecting portion toward the tip end is locatedradially inward of the friction welding portion, a burr is preventedfrom being generated inside the hollow product due to the frictionwelding.

[0021] According to a second aspect of the invention, there is provideda fluid processing system comprising hollow members joined to eachother, at least one of which is a hollow member having a processingfunction portion for subjecting fluid flowing into the hollow member toa predetermined processing, wherein one of the hollow member is formedwith a joining portion to be joined to the other hollow member byspinning working.

[0022] According to the second aspect, since the one hollow member isformed with the joining portion to be joined to the other hollow memberby the spinning working, it is possible to provide a light-weight fluidprocessing system having excellent flow efficiency in which the joiningportion is stably and reliably formed over the entire periphery of theone hollow member.

[0023] In the above aspect, the joining portion of the one hollow memberformed by the spinning working can be joined to the other hollow memberby friction welding.

[0024] With this arrangement, since the joining portion formed on theone hollow member is joined to the other hollow member by frictionwelding, it is possible to provide a fluid processing system forsubjecting the fluid flowing in the hollow member to a predeterminedprocessing in which the hollow member is easily and reliably joined overthe entire periphery regardless of the thickness of the hollow member, aweight of the hollow product is reduced, and the flow efficiency of thefluid is enhanced.

[0025] Further, any of the hollow members can be extended so as to bedisposed radially inward of the joining portion.

[0026] With this arrangement, burr is prevented from being generatedinside the hollow product due to the friction welding, and the inside isformed continuously. Therefore, it is possible to provide a fluidprocessing system having higher flow efficiency of the fluid.

[0027] According to a third aspect of the invention, there is provided amethod for joining hollow members to each other for allowing fluid toflow therein, comprising the steps of: forming a joining portion on oneof the hollow members by spinning working; and joining the joiningportion of the one hollow member to the other hollow member by frictionwelding.

[0028] With the third aspect, the one hollow member is formed with thejoining portion by the spinning working, and then the joining portion ofthe one hollow member and the other hollow member are joined to eachother by friction welding. Thus, it is possible to provide a joiningmethod of hollow members in which the hollow members are easily andreliably joined to each other over the entire periphery regardless ofthe thickness of the hollow member, and the flow efficiency of the fluidis excellent with reduced weight.

[0029] In the above aspect, in the step for joining the hollow member byfriction welding, the joining portion can be formed on the one hollowmember so that either one of the hollow members is disposed radiallyinward the joining portion.

[0030] With this arrangement, since one of the hollow members isextended so as to be disposed radially inward of the joining portion,burr is prevented from being generated inside the hollow product due tothe friction welding, and the inside is formed continuously. Therefore,it is possible to provide a joining method of hollow members havinghigher flow efficiency of the fluid.

[0031] Further, at least one of the hollow members can have a processingfunction portion for subjecting fluid flowing in hollow member to apredetermined processing.

[0032] With this arrangement, it is possible to provide a joining methodof hollow members which can be applied for manufacturing a fluidprocessing system for subjecting fluid flowing in the joined hollowmembers to a predetermined processing.

BRIEF DESCRIPTION OF THE DRAWINGS

[0033]FIG. 1 is an explanatory view showing a state in which a flangemember as a hollow member to which the-invention is applied is subjectedto burring processing to form a joining portion;

[0034]FIG. 2 is a front view of a burring apparatus;

[0035]FIG. 3 is a plan view of the apparatus shown in FIG. 2;

[0036]FIG. 4 is an explanatory view for sequentially showing shapes ofthe hollow member in each step according to a first embodiment;

[0037]FIG. 5 is an enlarged explanatory view showing the frictionwelding shown in FIG. 4;

[0038]FIG. 6 is an explanatory view of a modification of the firstembodiment of the invention in which a margin necessary for the frictionwelding is 1.5 times with respect to a plate thickness of a joiningportion of a container of a catalyst converter;

[0039]FIG. 7 is an enlarged explanatory view showing the frictionwelding shown in FIG. 6;

[0040]FIG. 8 is a sectional view for explaining a support apparatuswhich arranges and supports one hollow member and the other hollowmember such that center axes thereof coincide with a coaxial extensionline, and FIG. 8 shows a state before joining portions of both hollowmembers are joined to each other by friction welding;

[0041]FIG. 9 is an explanatory view for showing a state in which thejoining portions of both the hollow members are joined to each other bythe friction welding from the state shown in FIG. 8;

[0042]FIG. 10 is a sectional view for explaining a state in which acatalyst converter to which the flange member is joined is connected toa flange of another structure;

[0043]FIG. 11 is an explanatory view for showing a state in which theflange member is connected at a predetermined phase, to a container ofthe catalyst converter which is formed such that it is deviated inangle;

[0044]FIG. 12 is an explanatory view for sequentially showing shapes ofthe hollow member in each step according to a second embodiment;

[0045]FIG. 13 is an explanatory views for sequentially showing shapes ofthe hollow member in each steps according to a third embodiment;

[0046]FIG. 14 is an enlarged sectional view showing a state beforefriction welding of a modification of an embodiment shown in FIG. 13 iscarried out;

[0047]FIG. 15 is an explanatory view showing a state in which thejoining portions of both hollow members are connected to each other byfriction welding from the state shown in FIG. 13;

[0048]FIG. 16 is an explanatory view for sequentially showing shapes ofthe hollow member in each step according to a fourth embodiment;

[0049]FIG. 17 is an explanatory view for sequentially showing shapes ofthe hollow member in each step according to a fifth embodiment;

[0050]FIG. 18 is an explanatory view for sequentially showing shapes ofthe hollow member in each step according to a sixth embodiment;

[0051]FIG. 19 is a perspective view of an exhaust system for a vehicleto which the invention is applied, the system being separated into eachconstituent unit;

[0052]FIG. 20 is a sectional view for explaining related art in which aflange member is joined by cladding by welding; and

[0053]FIG. 21 is a sectional view for explaining a state in which a burris generated also on an inner side by joining a hollow member by aconventional friction welding.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0054] A first embodiment of the invention will be explained in detailbased on FIGS. 1 to 11. In this embodiment, an exhaust system of anengine of a Vehicle as shown in FIG. 19 comprises a catalyst converter 2(one of hollow members) which is one constituent unit for causingchemical reaction such as oxidation-reduction with respect to exhaustgas discharged from the engine and flowing through an exhaust manifold,thereby purifying the exhaust gas. The exhaust system also comprises acontainer 10 in which a catalyst carrier 12 (see FIG. 10) of thecatalyst converter 2 as a processing function portion is accommodated.The container 10 comprises an accommodating portion 10 a, cone portions10 b whose diameters are gradually reduced from the accommodatingportion 10 a, small-diameter connecting portions 10 c connected to theaccommodating portion 10 a through the cone portions lob. A method forjoining the connecting portions 10 c and the flanges 11 (other hollowmembers) to be fastened to flanges 21 of other constituent units 1 and 3will be explained.

[0055] The catalyst converter 2 which is the one constituent unit of theexhaust system as the hollow product of the invention is formed suchthat the one hollow member (connecting portion 10 c of the container 10of the catalyst converter 2 in which the catalyst carrier 12 isaccommodated) is formed, by spinning working, with a joining portion 15to be joined to a joining portion 16 of the other hollow member (flangemember 11). Further, the joining portion 15 which was formed by spinningworking is joined to the joining portion 16 of the other hollow member(flange member 11) by friction welding. One of the one hollow member(connecting portion 10 c of the container of the catalyst converter) andthe other hollow member (flange member 11) is extended such that one ofthem is disposed radially inward of the joining portions 15 and 16.

[0056] The joining method of the hollow members 10 and 11 of theinvention comprises a step for forming the joining portion 15 on the onehollow member (connecting portion 10 c of the container of the catalystconverter in which the catalyst carrier 12 is accommodated) by spinningworking, and a step for joining this joining portion 15 and the joiningportion 16 (of the flange member 11) of the other hollow member byfriction welding. In the spinning working step, one of the one hollowmember (connecting portion 10 c of the container of the catalystconverter) and the other hollow member (flange member 11) is extendedsuch that one of them is disposed radially inward of the joiningportions 15 and 16.

[0057] As shown in FIG. 1, the flange member 11 is formed such that aplate material which was formed into a predetermined shape is formedwith a hole 20 and a periphery of the hole 20 is subjected to burring,thereby forming the flange member 11 into a hollow structure throughwhich the connecting portion 10 c of the container of the catalystconverter can be inserted (in the case of this embodiment), and aportion thereof projects from one surface of the flange member 11. Inthis embodiment, the portion projecting from one surface of the flangemember 11 constitutes the joining portion 16 which is to be joined tothe joining portion of the catalyst converter which is formed as will bedescribed later. As shown in FIG. 10, the flange member 11 is formedwith an annular groove 11 a for accommodating a seal member 53 to keepthe air-tightness when the flange member 11 is abutted against andfastened to a flange member 51 which is another constituent unit bymeans of bolts 52. As shown in FIG. 10, the flange members 11 and 51 aresuch that one 11 of the flange members on the side of the catalystconverter 2 is formed with holes 11 b through which the bolts 52 areinserted, and the other one 51 is formed with female screw holes 51 athrough which the bolts 52 are threaded.

[0058] As shown in FIGS. 2 and 3, one example of an apparatus forcarrying out the burring working comprises a spindle 60 for retaining aplate material which will become the flange member 11 and for rotatingthe plate material around the hole 20, and a burring tool 61 which movesin a direction of rotational axis and a radial direction of the spindle60. The spindle 60 includes a pulley 65 around which and a pulley 63connected to a motor 62 is wound a belt 64, and a chuck 66 for retainingthe plate material which will become the flange member 11. The burringapparatus includes an axially moving table 69 which is moved by a feedscrew mechanism 68 driven by a servo motor 67, and a radially movingtable 72 which is provided on the axially moving table 69 and moved by afeed screw mechanism 71 driven by a servo motor 70. The burring tool 61is supported by the radially moving table 72. If the motor 62 is drivento rotate the spindle 60 through the belt 64, the plate material whichwill become the flange member 11 grasped by the chuck 66 is rotatedaround the previously formed hole 20. In this state, the servo motor 67is driven to move the axially moving table 69 forward (move the tableleftward in FIGS. 2 and 3), and the burring tool 61 is inserted into thehole 20 of the plate material which will become the flange member 11such that the burring tool 61 does not contact the hole 20 as shown inFIG. 1A. The servo motor 70 is driven to move the radially moving table72 outward in the radial direction, thereby bringing the burring tool 61into contact with an inner periphery of the hole 20 of the platematerial which will become the flange member 11. In this state, theservomotor 67 is driven to move the axially moving table 69 backward(rightward in FIGS. 2 and 3), and the inner periphery of the hole 20 isformed such that the inner periphery projects toward one side. Byrepeating the above steps, the hole 20 can be formed into a sizeallowing the connecting portion 10 c of the catalyst converter 2 to beinserted into the hole 20, and the hole 20 is formed such that thejoining portion 16 projects from one surface of the flange member 11.The burring apparatus is not limited to the embodiment shown in FIGS. 2and 3, as far as the burring tool can be relatively revolved around thehole 20 formed in the plate material which will become the flange member11.

[0059] As shown in FIG. 4, the container 10 of the catalyst converterintegrally comprises the tapered cone portion lob tapered from theaccommodating portion 10 a of the catalyst carrier 12 toward theopposite ends and the reduced-diameter connecting portions 10 c disposedat the opposite ends by repeatedly spinning working the pipe-like blankhaving a size capable of accommodating the catalyst carrier 12 whilerevolving a forming roller 81 relatively with respect to the pipe-likeblank. In this invention, as shown in FIG. 4A, by pinning working thepipe-like blank, at lest one cone portion 10 b and the connectingportion 10 c are formed into substantially the final shape and size, andas shown in FIG. 4B, a portion of each of the connecting portions 10 cfrom the cone portion 10 b to an axially intermediate portion of theconnecting portion 10 c are further drawn into a finally desired outerdiameter and then, the forming roller 81 is once retreated radiallyoutward. Then, as shown in FIG. 4C, the forming roller 81 is moved fromthe tip end of the connecting portion 10 c to the axially intermediateportion, and that portion is drawn into the finally desired outerdiameter. The portion of the connecting portion 10 c on the side of thecone portion lob and the tip end are reduced in diameter, and a materialof the blank is gathered toward the axially intermediate portion of theconnecting portion 10 c at the time of diameter reduction. Therefore,the annular joining portion 15 is reliably formed at the axiallyintermediate portion of the connecting portion 10 c over the entireperiphery so as to project radially outward. An amount of projection ofthe joining portion 15 radially outward can be adjusted by a diameterreducing amount of the connecting portion 10 c on the side of the coneportion lob and the tip end side of the connecting portion 10 c towardthe axially intermediate portion, and a gathering amount of thematerial.

[0060] Next, as shown in FIG. 4D, the pipe-like blank which will becomethe container 10 of the catalyst converter formed with the connectingportion 10 d having one of the cone portions lob and the joining portion15, and the flange member 11 formed with the joining portion 16 byburring working are arranged and supported by a support apparatus 82such that center axes thereof coincide with the coaxial extension line.The support apparatus 82 includes a chuck 90 for holding the flangemember 11 mounted to a spindle (not shown) rotated about its axis and ashaft 92 pivoted by a bearing 91 provided at a center of the chuck 90.The flange member 11 held by the chuck 90 and the shaft 92 canrelatively rotate. The shaft 92 is formed into such a size that theshaft 92 can be insertingly fit into the connecting portion 10 c at theend of the container 10 of the catalyst converter 2 for supporting thesame. A tip end of the shaft 92 is tapered to form an angle of about 5to 15° with respect to an inner peripheral surface of the connectingportion 10 c. In the case of this embodiment, the connecting portion 10c formed at the end of the container 10 of the catalyst converter 2 isnon-rotatably clamped and fixed by a clamper 93 as shown in FIGS. 4D and4E. The spindle (not shown) provided with the chuck 90 and the shaft 92as well as the clamper 93 for clamping the container 10 of the catalystconverter 2 can move relatively in the axial direction.

[0061] In a state in which the connecting portion 10 c of the containerof the catalyst converter is non-rotatably clamped by the clamper 93 andthe flange member 11 is held by the chuck 90, if the spindle (not shown)provided with the chuck 90 is rotated about its axis thereby rotatingthe flange member 1, the flange member 11 and the container 10 of thecatalyst converter are relatively moved closer to each other in theaxial direction while rotating the flange member 11, the shaft 92 isfirst inserted from the end of the connecting portion 10 c of thecontainer of the catalyst converter, and the flange member 11 arealigned to each other. Since the shaft 92 is rotatably supportedindependent from the flange member 11 held by the chuck 90, the shaft 92does not rotate relative to the clamped container 10 of the catalystconverter. Accordingly, friction heat does not generate between thecontainer 10 of the catalytic converter and the shaft 92. Therefore,even if a thickness t of the container 10 of the catalyst converter isthin, it is possible to prevent the container 10 of the catalystconverter from being melted and damaged by the friction heat.

[0062] If the container 10 of the catalyst converter and the flangemember 11 are relatively moved closer to each other in the axialdirection, the connecting portion 10 c of the container of the catalystconverter is inserted into the flange member 11. As shown in FIGS. 4E, 5or 9, contacted end surfaces of both joining portions 15 and 16 aresoftened by applying a pushing force to a predetermined margin Y with apredetermined upset pressure, thereby carrying out the friction welding.By carrying out the friction welding, burrs are generated on bothjoining portions 15 and 16. In this invention, however, since thejoining portion 15 is formed at the axially intermediate portion of theconnecting portion 10 c of the container of the catalyst converter,i.e., since a portion 10 d between the joining portion 15 and the tipend of the connecting portion 10 c extends to a position inside of theflange member 11 when the connecting portion 10 c of the container ofthe catalyst converter is inserted into the flange member 11 forcarrying out the friction welding, the portion 10 d is disposed radiallyinward of the joining portions 15 and 16. Therefore, the burr isgenerated only outside in the radial direction of both the joiningportions 15 and 16, and no burr is generated inside the catalystconverter 2. The burr generated outside in the radial direction of boththe joining portions 15 and 16 can easily be removed if necessary. Thecontainer 10 of the catalyst converter and the joining portions 15 and16 of the flange 11 are joined air-tightly over the entire periphery bycarrying out the friction welding.

[0063] Here, as shown in FIG. 7, if the margin Y which is necessary forthe friction welding is 1.5 time greater than the thickness t of theconnecting portion 10 c of the container of the catalyst converter, itis difficult to form the joining portion 15 having the axial thicknesscorresponding to the margin Y only by the diameter reducing amount ofthe connecting portion 10 c from its portion on the side of the coneportion lob and its portion from the tip end toward the axiallyintermediate portion, and by the gathering amount of the material.Therefore, in such a case, as shown in FIG. 6A, an annular projection15′ projecting radially outward is formed on the axially intermediateportion of the connecting portion 10 c of the container of the catalystconverter such that its projecting amount is greater than that of thejoining portion 15 shown in FIGS. 4 and 5, and the spinning working iscarried out such that the projection 15′ is inclined toward the tip endof the joining portion by the forming roller as shown in FIG. 6B. Withthis arrangement, as shown in FIGS. 7A and 7B, it is possible to formthe joining portion 15 having the axial thickness 1.5 time greater thanthe thickness t capable of sufficiently corresponding to the margin Ynecessary for the friction welding.

[0064] This invention is not limited to the above embodiment, and thecontainer 10 of the catalyst converter 2 and both the joining portions15 and 16 of the flange member 11 may be relatively rotated. In thisfriction welding, it is preferable that the relative rotation number andpushing speed of the flange member 11 and the connecting portion 10 c ofthe container of the catalyst converter are kept constant until plasticflowing layers are formed on abutting surfaces of both the joiningportions 15 and 16 and then, the relative rotation number is reduced ata predetermined speed-reduction ratio until the rotation is stopped, andthe pushing force is stopped thereafter.

[0065] If the container 10 of the catalyst converter 2 is formed at itsone side with the cone portion 10 b and the connecting portion 10 c bythe spinning working, the catalyst carrier 12 is inserted from the otherside end. This other side ends is subjected to the spinning workingsimilarly, and the cone portion 10 b and the connecting portion 10 c areintegrally formed. The other side connecting portion 10 c is also formedwith the same joining portion 15, and this joining portion 15 is joinedto the joining portion 16 of the flange member 11 by friction welding.In the container 10 of the catalyst converter 2 of the embodiment shownin FIGS. 4 to 7, the one joining portion 15 is joined such as toslightly project from the flange member 11. Therefore, as shown in FIG.10, the other constituent unit to be connected to the connecting portion10 c is joined such as to slightly project from the tip end of aconnecting portion 50 of the hollow member such as a pipe of the otherconstituent unit. Thus, when the flange members 11 and 51 are fastenedto each other, ends of both connecting portions 10 c and 50 abut againsteach other in the flange member 51 of the other constituent unit.

[0066] In addition to the above-described embodiment, the invention canalso be applied to a state in which the axis of the connecting portion10 c of the container of the catalyst converter is inclined with respectto the axis of the accommodating portion 10 a of the catalyst carrier 12at a predetermined angle as shown in FIG. 11. In this case, at the timeof the friction welding, by setting the phase for stopping the relativerotation of the flange member 11 with respect to the connecting portion10 c, it is possible to join the flange member 11 at a phase positionset with respect to the inclined catalyst converter 2 so that the flangemember 11 can coincide with the phase of the flange member 51 of theother constituent unit.

[0067] Next, a second embodiment of the invention will be explainedbased on FIG. 12. In the following description, only portion differentfrom the above embodiment will be explained, and the same orcorresponding portions will be designated with the same symbols, andexplanation thereof will be omitted.

[0068] In this embodiment, as shown in FIG. 12A, the pipe-like blank issubjected to spinning working so that at least one of the cone portion10 b and the connecting portion 10 c is formed into the final shape andsize as shown in FIG. 12B. Then, as shown in FIG. 12C, the connectingportion 10 c from its axially intermediate portion to the tip endportion 10 d is reduced in diameter to such a degree that the connectingportion 10 c can be inserted into the flange member 11 by means of thespinning working, thereby drawing a step-like joining portion 15 overits entire periphery. The radial size of the step-like joining portion15 of the connecting portion 10 c is set such that the connectingportion 11 c can be inserted into the flange member 11 and theconnecting portion 10 c can be friction welded to an end face projectingfrom one surface of the flange member 11 which will become the joiningportion 16. Then, as shown in FIG. 12D, the flange member 11 formed withthe joining portion 16 and the pipe-like blank which will become thecontainer 10 of the catalyst converter 2 formed with the connectingportion 10 c having the one cone portion 10 b and the joining portion 15are disposed by the support apparatus such that the center axes thereofcoincide with the coaxial extension line. In a state in which thecontainer 10 of the catalyst converter is clamped and fixed by a clamper93, the flange member 11 is moved in the axial direction while beingrotated, the flange member 11 is insertingly fit outside the connectingportion 10 c of the container of the catalyst converter. Then, as shownin FIG. 12E, the friction welding is carried out for softening andwelding the contacted end surfaces of the joining portions 15 and 16 byapplying a pushing force to a predetermined margin Y with apredetermined upset pressure. At that time, since the reduced-diameterportion 10 d of the connecting portion 10 c is extended toward theflange member 11 and located radially inward of the joining portions 15and 16, like the above embodiment, a burr is generated only radiallyoutside of the joining portions 15 and 16 when the friction welding iscarried out, and no burr is generated inside the catalyst converter 2.

[0069] Next, a third embodiment of the invention will be explained basedon FIGS. 13 to 15. In the following description, only portion differentfrom the above embodiment will be explained, and the same orcorresponding portions will be designated with the same symbols, andexplanation thereof will be omitted.

[0070] In this embodiment, as shown in FIG. 13A, the pipe-like blank issubjected to spinning working so that at least one of the cone portion10 b and the connecting portion 10 c are formed into the final shape andsize as shown in FIG. 13B. A size of a portion which will become thestep-like joining portion 15 is set such that the portion projectingfrom one surface of the flange member 11 can be inserted into joiningportion 15. Next, as shown in FIG. 13C, a portion of the connectingportion 10 c from the cone portion 10 b to the axially intermediateportion is further drawn into the finally desired outer diameter, andthe forming roller 81 is once retreated radially outward. The connectingportion 10 c of the container of the catalyst converter is formed suchthat a diameter of the portion 10 d of the connecting portion 10 c fromthe axially intermediate portion to the tip end thereof is increasedrelatively over the entire periphery. In the case of this embodiment,the joining portion 15 of the container 10 of the catalyst convertercomprises a tip end surface and an inner peripheral surface of theconnecting portion 10 c formed so as to be increased in diameterrelatively. The joining portion 16 of the flange member 11 comprises aperiphery of a portion projecting from one surface thereof and an outerperipheral surface of this portion. It is preferable to set an innerdiameter of the connecting portion 10 c from the cone portion 10 b tothe axially intermediate portion thereof and an inner diameter of theflange member 11 substantially equal to each other. The tip end of theportion projecting from the one surface of the flange member 11 is setsuch that it does not come into contact with the connecting portion 10 cof the container of the catalyst converter.

[0071] Then, as shown in FIG. 13D, the pipe-like blank which will becomethe container 10 of the catalyst converter formed with the connectingportion 10 c having one cone portion 10 b and the joining portion 15 andthe flange member 11 formed with the joining portion 16 are supported bythe support apparatus, and the center axes are disposed so as tocoincide with the coaxial extension line. In a state in which thecontainer 10 of the catalyst converter is clamped and fixed by a damper93, the flange member 11 is moved in the axial direction while beingrotated, the flange member 11 is insertingly fit outside the connectingportion 10 c of the container of the catalyst converter. Then, as shownin FIG. 13E, the friction welding is carried out for softening andwelding the contacted end surfaces of both the joining portions 15 and16 by applying a pushing force to a predetermined margin with apredetermined upset pressure. At that time, since the portion of theflange member 11 projecting from one surface thereof is extended towardthe connecting portion 10 c of the container of the catalyst converterand located radially inward of both the joining portions 15 and 16, likethe above embodiment, a burr is generated only radially outside of thejoining portions 15 and 16 when friction welding is carried out, and noburr is generated inside the catalyst converter 2. When the innerdiameter of the flange member 11 and the inner diameter of theconnecting portion 10 c from the cone portion 10 b to the axiallyintermediate portion are set substantially equal to each other, it ispossible reduce the flow resistance of the fluid such as exhaust gasflowing through the exhaust system.

[0072] In this embodiment, as shown in FIGS. 14 and 15, it is preferableto form a groove 11 c in an outer periphery of a base end of a portionprojecting from one surface of the flange member 11. By forming thegroove 11 c, at a time of friction welding the joining portions 15 and16, a material of the connecting portion 10 c of the container of thecatalyst converter is softened, and the material flows into the groove11 c of the flange member 11 and is welded. Therefore, it is possible tostrengthen the junction between the flange member 11 and the connectingportion 10 c of the container of the catalyst converter.

[0073] Next, a fourth embodiment of the invention will be explained withreference to FIG. 16 based on a case in which both the hollow members tobe joined are pipes 30 and 31 used in an exhaust system or the like. Inthe following description, only portion different from the aboveembodiment will be explained, and the same or corresponding portionswill be designated with the same symbols, and explanation thereof willbe omitted.

[0074] In each of FIGS. 16A, 16B, 16D, and 16E, a left side pipe will bereferred to as “one pipe 30,” and a right side pipe will be referred toas “the other pipe 31.” As shown in FIG. 16A, straight pipes havingsubstantially the same diameter are used as the pipes 30 and 31.

[0075] As shown in FIG. 16B, the forming roller 81 is moved rightward inFIG. 16B by a predetermined length in the axial direction from apredetermined position in the vicinity of a tip end toward the tip endof the one pipe 30 while relatively revolving the forming roller 81, soas to subject the one pipe 30 to spinning working to reduce itsdiameter. Next, as shown in FIG. 16C, the forming roller is movedleftward in FIG. 16C by a predetermined length in the axial directionfrom the tip end of the one pipe 30 while relatively revolving theforming roller 81 so as to subject the one pipe 30 to spinning workingto reduce its diameter. With this operation, the annular joining portion15 projecting radially outward is formed on a portion of the one pipe 30in the vicinity of the tip end. When portions of the joining portion 15in FIG. 16 to its left and right are reduced in diameter, material ofone pipe 30 is gathered by moving the forming roller 81 toward thejoining portion 15 in the axial direction. Therefore, the joiningportion 15 can have sufficient thickness in the axial direction and inthe radial direction for friction welding with respect to the joiningportion 16 of the other pipe 31.

[0076] As shown in FIG. 16B, the forming roller 31 is moved leftward inFIG. 16B by a predetermined length in the axial direction from apredetermined position in the vicinity of a tip end toward the tip endof the other pipe 31 while relatively revolving the forming roller 81,so as to subject the other pipe 31 to spinning working to reduce itsdiameter. An original diameter of the tip end of the other pipe 31 ismaintained, and the joining portion 16 is constituted by a tip endsurface of the other pipe 31.

[0077] As shown in FIG. 16D, both the pipes 30 and 31 formed in theabove-described manner are disposed such that their center axes coincidewith the coaxial extension line, they are moved in the axial directioncloser to each other while rotating relatively about the axis. As shownin FIG. 16E, the one pipe 30 is inserted into the other pipe 31, andfriction welding is carried out by softening and welding the contactedend surfaces of the joining portions 15 and 16 by applying a pushingforce to a predetermined margin Y with a predetermined upset pressure.At that time, since a portion 30 d of the one pipe 30 extends from thejoining portion 15 to the tip end so as to be positioned radially inwardof the joining portions 15 and 16, a burr is generated only radiallyoutside the joining portions 15 and 16, and no burr is generated insidethe pipes 30 and 31.

[0078] Next, a fifth embodiment of the invention will be explained withreference to FIG. 17 based on a case in which the hollow members to bejoined are inner pipe 40 and an outer pipe 41 constituting a doublehollow product used for the catalyst converter 2 of the exhaust system.In the following description, only portion different from the aboveembodiment will be explained, and the same or corresponding portionswill be designated with the same symbols, and explanation thereof willbe omitted.

[0079] In this embodiment, as shown in FIG. 17A, a pipe-like blankhaving a size capable of accommodating the catalyst carrier 12 issubjected to spinning working while revolving the forming roller 81relatively. Accordingly, the inner pipe 40 is integrally formed withcone portions 40 b which is tapered toward opposite ends of the innerpipe 40 from an accommodating portion 40 a of the catalyst carrier 12and reduced-diameter connecting portions 40 c disposed on opposite ends.An end of each of the connecting portion 40 c is increased in diameterradially outward, thereby forming the joining portion 15. As shown inFIG. 17B, a cylindrical blank constituting the outer pipe 41 is disposedoutside of the inner pipe 40 formed in this manner at a predetermineddistance from the accommodating portion 40 a of the catalyst carrier 12of the inner pipe 40 in the radial direction. Then, as shown in FIG.17C, by repeatedly subjecting the outer pipe 41 to the spinning workingwhile revolving the forming roller 81 relatively, the outer pipe 41 isreduced in diameter while maintaining a predetermined distance in theradial direction between the accommodating portion 40 a for the catalystcarrier 12, the tapered cone portions 40 b, and the connecting portions40 c of the inner pipe 40. At that time, an end of the outer pipe 41substantially coincides with a boundary of the diameter-increasedportion 15 of the end formed on the connecting portion 40 c of the innerpipe 40, which constitutes the joining portion 16. Thereafter, as shownin FIG. 17D, by carrying out the spinning working while revolving theforming roller 81, the diameter-increased portion of the end formed onthe connecting portion 40 c of the inner pipe 40 is turned back, and theend of the outer pipe 41 is sandwiched and clamped between theconnecting portion 40 c of the inner pipe and the turned back portion 15in such a manner that air-tightness can be maintained.

[0080] In a state in which the end 16 of the outer pipe 41 is sandwichedand clamped between the connecting portion 40 c of the inner pipe andthe turned back portion 15, the inner pipe 40 and the outer pipe 41 arepressed by the forming roller 81 while being relatively revolved aboutthe axis, and the joining portions 15 and 16 of both the pipes 40 and 41are joined to each other by the friction welding.

[0081] Next, a sixth embodiment of the invention will be explained withreference to FIG. 18 based on a case in which the hollow members to bejoined are inner pipe 40′ and an outer pipe 41′ constituting a doublestraight pipes used for the exhaust system. In the followingdescription, only portion different from the above embodiment will beexplained, and the same or corresponding portions will be designatedwith the same symbols, and explanation thereof will be omitted.

[0082] In this embodiment, as shown in FIG. 18A, by moving the formingroller 81 in the axial direction with respect to the pipe-like blank soas to gather material thereof toward an axially intermediate positionwhile relatively revolving the forming roller 81, an annular projection15′ projecting radially outward for constituting the joining portion 15is formed on the inner pipe 40′ in its axially intermediate portion. Asshown in FIG. 18B, the outer pipe 41′ is fitted over the inner pipe 40′formed with the projection 15′ at a predetermined distance from theinner pipe 40′ in the radial direction. Then, as shown in FIG. 18C, anend of the outer pipe 41′ is reduced in diameter so that the end comesinto contact with the projection 15′ of the inner pipe 40′ by relativelyrevolving the forming roller 81. Thereafter, the projection 15′ formedon the inner pipe 40′ is inclined while relatively revolving the 81, anend of the outer pipe 41′ is sandwiched and clamped between the joiningportion 15 formed by the projection 15′ and an outer peripheral surfaceof the inner pipe 40′, thereby joining the two pipes. In this embodimentalso, like the embodiment shown in FIG. 17, the inner and outer pipesare pushed by the forming roller 81 while relatively rotating the pipesabout the axis, and the joining portions 15 and 16 of both the pipes 40′and 41′ can be joined to each other by friction welding.

[0083] The invention is not limited to the above embodiments, and can beapplied to a system requiring flow efficiency of fluid. That is, theinvention is suitable for a fluid processing system having a functionalmaterial as the processing function portion for subjecting flowing fluidto a predetermined processing by bringing the fluid into contact withthe function material to exert physical effect and/or chemical effect onthe fluid. Application includes, in addition to the catalyst for causingchemical reaction such as oxidation-reduction with respect to exhaustfluid as the processing function portion, an exhaust system having amuffler for reducing noise, and an intake system having a filter forphysically separating the intake fluid. The invention can also beapplied to other fluid processing system such as a combustion engineother than one for a vehicle only if the system has a processingfunction portion for subjecting flowing fluid to a predeterminedprocessing. The fluid itself is not limited to gas, and the state ofmaterial is not limited as long as the fluid has flowability such asmixture of liquid and gas and/or liquid and power including small solid.

1. A hollow product comprising hollow members joined to each other forallowing fluid to flow therein, wherein one of said hollow member isformed with a joining portion to be joined to the other hollow member byspinning working.
 2. A hollow product according to claim 2, wherein saidjoining portion of said one hollow member formed by the spinning workingis joined to said other hollow member by friction welding.
 3. A hollowproduct according to claim 2, wherein either one of said hollow membersis extended so as to be disposed radially inward of said joiningportion.
 4. A fluid processing system comprising hollow members joinedto each other, at least one of said hollow members having a processingfunction portion for subjecting fluid flowing in said hollow member to apredetermined processing, wherein one of said hollow members is formedwith a joining portion to be joined to the other hollow member byspinning working.
 5. A fluid processing system according to claim 4,wherein said joining portion of said one hollow member formed by thespinning working is joined to said other hollow member by frictionwelding.
 6. A fluid processing system according to claim 5, whereineither one of said hollow members is extended so as to be disposedradially inward of said joining portion.
 7. A method for joining hollowmembers to each other for allowing fluid to flow therein, comprising thesteps of: forming a joining portion on one of said hollow members byspinning working; and joining said joining portion of said one hollowmember to the other hollow member by friction welding.
 8. A joiningmethod according to claim 7, wherein at least one of said hollow memberhas a processing function portion for subjecting fluid flowing in hollowmember to a predetermined processing.
 9. A joining method according toclaim 7, wherein in said step for joining the hollow member by frictionwelding, the joining portion is formed on said one hollow member so thateither one of said hollow members is disposed radially inward of saidjoining portion.
 10. A joining method according to claim 9, wherein atleast one of said hollow member has a processing function portion forsubjecting fluid flowing in hollow member to a predetermined processing.